The invention is generally related to labeling machinery and adhesive applicators for use therewith, and to the application of adhesive to label material, e.g., for use on articles such as beverage containers and the like. The invention is also related to the feeding of containers through labeling machinery and the like, particularly using starwheel container transport mechanisms.
In a great number of consumer product markets, particularly those which are low-margin and/or price-driven, an ongoing need exists for various manners of reducing product costs. For example, just-in-time manufacturing techniques, which reduce costs through minimizing inventory, have grown in prominence. In addition, improved packaging techniques and materials are constantly being developed to minimize the packaging component of product costs.
Just-in-time manufacturing can place significant demands on product manufacturing and packaging equipment due to the quick turnaround that is often required to timely fill customer orders. As a result, there is an ongoing need for a manner of increasing the speed of product manufacturing and packaging equipment so that inventory costs can be reduced without adversely impacting a manufacturer""s ability to fill customer orders in a timely fashion.
For example, for bottled beverages such as soft drinks, beer, juice, liquor, etc., significant efforts have been expended in attempting to lower the costs associated with applying product labels to beverage containers such as glass bottles, plastic bottles, aluminum cans, and the like. A particularly cost-effective manner of labeling beverage containers utilizes a continuous web of pre-printed polymer label material that is cut into predetermined lengths, supplied with adhesive, and applied directly to the surface of a container. Adhesive costs may also be reduced by applying adhesive only to the leading and trailing edges of individual labels and wrapping the labels completely around the containers.
High speed operation of continuous-feed labeling machinery, in particular, requires careful control over labels as they are fed from the supply roll, cut from the web, supplied with adhesive and applied to containers. In most continuous-feed labeling machinery, labels are transferred from station to station by a sequence of rollers and drums. A variety of mechanisms, including web tension, mechanical clamps and fingers, and vacuum surfaces, are typically used to assist in the transfer of labels (whether severed or unsevered from a web) from station to station.
Pressurized air is also used in some labeling machinery to improve label control. For example, pressurized air directed toward the leading edge of a label may be used to assist in directing the label from a cutter drum to a transport drum after the label has been severed from a web, or to assist in directing the label from a transport drum to the surface of a container. Also, in some applications pressurized air may be supplied to an unsupported portion of the backside of a seam formed between the leading and trailing edges of a label wrapped around a non-cylindrical article, to strengthen the bond between the leading and trailing edges.
One area of particular concern for many labeling applications is controlling the feed of labels during the application of adhesive. Adhesive applicators used are typically utilized to deposit an adhesive material such as a hot melt or pressure sensitive glue composition to a label immediately prior to placing the label on a container. Typically, such applicators include an adhesive roller that forms a nip with a label transport. mechanism such as a vacuum drum, and that is supplied with a source of adhesive on its outer periphery such that adhesive is applied to a label supported on the transport mechanism as the label is fed past the adhesive roller.
One difficulty associated with conventional adhesive applicators is that the leading edge of a label can in some instances separate from the surface of the transport mechanism and follow the adhesive roller as the leading edge of the label exits the nip formed by the adhesive roller and the underlying transport mechanism. When this occurs, the label will often jam the adhesive applicator and the remainder of the labeling machinery, resulting in defective product and downtime associated with cleaning and restarting the machine.
To address this concern, some adhesive applicators utilize mechanical devices such as a series of parallel wires adjacent an adhesive roller to keep the leading edge of a label from wrapping around the roller. However, in many instances the parallel wires leave undesirable patterns on the adhesive applied to each label. Further, glue droplets on the wires can contaminate both the labels and the transport mechanism. Misadjusted wires can also wrinkle or displace labels on the transport mechanism, resulting in defective labeled articles.
Other labeling machinery designs utilize mechanical hold down devices such as clamps or fingers on a transport mechanism to hold down the leading edge of each label as the label passes an adhesive applicator. Moreover, in some designs in which labels are transported past an adhesive applicator via a vacuum drum, a relatively high level of vacuum is used to resist the adherence of labels to the adhesive applicator. However, mechanical hold down devices and the like are often mechanically complex and can negatively impact performance and reliability. Increased vacuum levels can induce stretching of the label material and necessitate the use of larger and more expensive vacuum pumps.
Another difficulty associated with conventional adhesive applicators is the overspray of adhesive that often occurs during the application of adhesive to the trailing edge of a label. In particular, when a label passes through the nip between an applicator roller and a transport mechanism, the trailing edge (which is supported on the surface of the transport mechanism) may be separated from the roller by a gap across which excess adhesive may spray. A portion of the adhesive may deposit on the surface of the transport mechanism, resulting in contamination of the mechanism. Unless the overspray is periodically cleaned from transport mechanism, the transport mechanism may jam and halt the machine, requiring a more extensive and time consuming cleaning and restart operation. Given that any downtime negatively impacts the efficiency and productivity of labeling machinery, cleaning operations of any type are often highly undesirable.
Therefore, a substantial need exists in the art for an improved manner of feeding labels through labeling machinery, and in particular to improve the reliability of the application of adhesive to labels.
High speed operation of continuous-feed labeling machinery also requires careful control over the containers to which labels are applied. Considerable development efforts, for example, have been expended in improving the handling of containers, whether filled or empty, during a label application operation. Containers are typically fed to and from a labeling machine via a conveyor. Infeed and discharge mechanisms are typically used to transport containers from the conveyor, past a label transport mechanism, and back onto the conveyor.
Significant development efforts have been directed to the infeed mechanism at the head of a labeling machine, incorporating feed screws, starwheels, belts and the like to remove containers from a conveyor and pass the containers past the label transport mechanism with a desired amount of separation. Starwheels, for example, are toothed wheels that carry containers around an arcuate guide within the gaps formed between adjacent teeth, also referred to as pockets. In some implementations, multiple starwheels are used, e.g., where a small flow starwheel introduces initial gaps between incoming containers so that the containers can be picked up by a relatively larger infeed starwheel for transportation past a label transport drum.
One potential problematic characteristic of a starwheel, however, is that in some instances gaps can exist between a container, the starwheel and the guide around which the container is transported. At high speed, the presence of gaps can introduce vibrations and jeopardize the stability of the containers fed through the labeling machine, possibly causing container misfeeds and jamming of the machine.
In addition, at the discharge end of a labeling machine, comparatively less attention has been devoted to the stability of containers transported back onto a conveyor after being labeled. With many labeling machines, for example, labels are rolled onto a container by sandwiching the container between a fixed arcuate guide and a rotating label transport drum. Once a label is applied, one or more moving belts located downstream of the drum contact the containers and attempt to cancel out the spinning of the container before the container is returned to the conveyor. However, at higher speeds, belts may not provide adequate stability, particularly with lightweight containers having relatively high centers of gravity (e.g., unfilled two liter plastic beverage containers). Misfeeds of containers may occur, jamming the machine and requiring a time consuming cleaning and restart operation.
Other labeling machines utilize turrets (which grasp the top and bottom of each container) to transport containers past a label transport drum. In some designs, a discharge starwheel is used to transport containers between a turret and a conveyor. However, discharge starwheels used in such designs simply maintain the same separation of containers between the turret and the conveyor. Whenever containers on a conveyor are separated from one another, the risk of a container falling and creating a xe2x80x9cdominoxe2x80x9d effect in the line is increased.
Therefore, a significant need also continues to exist for an improved manner of reliably transporting containers through labeling machinery, and in particular, to improve the stability of containers transported by infeed and discharge mechanisms of a labeling machine during high speed operations.
The invention addresses these and other problems associated with the prior art by providing an apparatus and method that provides a number of unique enhancements to facilitate the performance and reliability of a labeling machine, particularly during high speed labeling operations. However, each of these enhancements can be utilized independent of the other enhancements in other applications.
Consistent with one aspect of the invention, a fluid dispenser is used in connection with an adhesive applicator to improve the reliability of label feed by a label transport mechanism during the application of adhesive to a label. The fluid dispenser is configured to direct a flow of fluid toward a nip formed between an adhesive roller on the applicator and the label transport mechanism, and from a position upstream from the nip. Among other advantages that will become more apparent below, doing so reduces the likelihood that the label will undesirably follow the adhesive roller upon the application of adhesive to the label.
Consistent with another aspect of the invention, a starwheel is provided including a rotatable hub and an engagement surface defining a pocket configured to engage an article. The engagement surface is resiliently coupled to the rotatable hub to move between first and second positions to vary a rotational position of the pocket relative to the hub. Among other applications, the starwheel may be used to control the flow of articles to a second, infeed starwheel in a labeling machine in such as manner that the clearance between the articles and the infeed components is minimized, thereby reducing article vibrations and improving stability.
Consistent with yet another aspect of the invention, a discharge starwheel is utilized to transfer articles from the discharge end of an arcuate guide that opposes a label transfer drum. The drum and arcuate guide adhere a label to an article by cooperatively wrapping the label around the article as the article rolls between the drum and arcuate guide. In some applications, careful control of configuration of the pockets on the discharge starwheel can improve the stability of discharged articles through reducing the spin imparted on articles by the label application process and/or decelerating the articles for pickup by a downstream discharge mechanism.
Consistent with still another aspect of the invention, a discharge starwheel may be utilized intermediate a label application station and a conveyor. The discharge starwheel may include a plurality of teeth defined about a perimeter thereof, with each tooth having a profile that decreases the separation between successive articles between the label application station and the conveyor. By reducing the separation between articles, greater stability on a conveyor may be obtained, as adjacent articles tend to support one another downstream of the label application station.
These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the drawings, and to the accompanying descriptive matter, in which there is described exemplary embodiments of the invention.